1. Field of the Invention
The present invention relates to electronic equipment enclosures for housing telecommunications, signaling, and other similar electronic equipment. More particularly, the present invention relates to such an electronic equipment enclosure which provides a greater range of possible mounting orientations and an ability to pivot or tilt while mounted; reduces crosstalk through separation of transmit and receive terminals; allows for convenient top access to both protective circuitry and test circuitry; provides improved pathways for thermal conduction, as well as other heat dissipation features; and prevents inadvertent disengagement of the electronic equipment due, for example, to movement or rough handling of the equipment enclosure.
2. Description of the Prior Art
It is often necessary to house telecommunications, signaling, and other similar electronic equipment in protective electronic equipment enclosures so that the equipment may be located where needed, often in relatively harsh operating environments such as mounted on telephone poles or within subterranean manholes. Thus, these equipment enclosures must be designed to protect the electronic equipment from environmental hazards, such as sun, moisture, dust, and debris, as well as damage from vandalism and attempted theft.
For example, ever-increasing use of wide area networks (WANs), particularly the Internet, and other telecommunication innovations has increased ISDN, (X)DSL, and T1, in homes and businesses. Due to signal propagation limitations, these digital services require special electronic equipment, including repeaters and doublers, to regenerate signals when end users are too far from a provider""s central office. Thus, it is important that the equipment enclosures safely and securely house multiple repeater units or xe2x80x9ccardsxe2x80x9d or other similar electronic equipment in a space efficient manner.
Unfortunately, many prior art equipment enclosures suffer from a number of disadvantages, including being undesirably limited with regard to possible mounting orientations, and an inability to maneuver the mounted equipment enclosure for easier access to the interior thereof. Furthermore, the prior art suffers from undesirable crosstalk and other interference problems due to interfering transmit and receive wires. One known solution to this latter problem is to twist the transmit and receive wires about one another at a rate of approximately two twists per inch, thereby substantially eliminating the interfering electromagnetic fields generated by the wires. Additionally, many prior art equipment enclosures do not provide for convenient access to either protective circuitry, such as lightning surge protection circuitry, or test circuitry, often requiring that a substantial portion of the electronic equipment be removed or its function otherwise disrupted in order to access one or both circuitries.
It is also important that the equipment enclosure facilitate dissipation of potentially damaging levels of heat generated by the operating electronic equipment. Electricity to power fans or other artificial cooling means is typically not available to the equipment enclosures and so dissipation of heat that can reach temperatures over 200xc2x0 F. must be accomplished through natural conduction and convection to ambient air. Such passive heat dissipation has become increasingly more difficult, however, as the electronic equipment has become faster, more powerful, and smaller, thereby generating greater amounts of potentially damaging heat in increasingly confined or sun-exposed operating environments. Unfortunately, another problem with existing equipment enclosure designs is that they do not make the most efficient use of natural cooling mechanisms. For example, in many prior art equipment enclosures, cooling problems are exacerbated by repeater card arrangements that retain generated heat and, furthermore, transfer the generated heat between adjacent cards and other electronic equipment rather than to the surrounding environment. Many such equipment enclosures attempt to compensate with complex mechanical linkage assemblies meant to provide a continuous pathway for thermal conduction to the ambient environment. Unfortunately, such mechanical linkages are typically expensive to manufacture, difficult to use, and undesirably increase the size and weight of the equipment enclosures.
Additionally, it is desirable that the electronic equipment be readily accessible and conveniently removable without being prone to inadvertent disengagement during, for example, movement or rough handling of the equipment enclosure. A variety of retaining mechanisms are known in the art, most of which include an actuatable or removable mechanism associated with each piece of electronic equipment. Unfortunately, though preventing inadvertent disengagement of the electronic equipment, these existing mechanisms typically result in additional time and labor required to remove the electronic equipment when desired.
Due to the above-identified and other problems and disadvantages in the prior art, a need exists for an improved electronic equipment enclosure.
The present invention solves the above-described and other problems and disadvantages to provide a distinct advance in the art of electronic equipment enclosures. More particularly, the present invention provides an electronic equipment enclosure for housing electronic equipment, such as, for example, telecommunications, signaling, and other similar electronic equipment, wherein the equipment enclosure provides a number of advantages over the prior art, including more effectively dissipating excess heat, thereby prolonging the life of the electronic equipment and preventing premature failure thereof due to damaging levels of retained, internally generated heat. This is accomplished in part by providing improved pathways for thermal conduction without use of complex, expensive, and heavy mechanical linkage assemblies found in the prior art.
In a preferred embodiment, the enclosure comprises an outer housing; a mounting bracket; a pivot bracket; a plurality of sleeves, with each sleeve being associated with a plurality of transmit terminals, a plurality of receive terminals, protective circuitry, and test circuitry; a spreader plate; and a heat sink or card retainer. The stainless steel outer housing is operable to internally house and protect the electronic equipment from environmental hazards as well as damage from vandalism and attempted theft. The outer housing further provides mounting and interface structures for coupling with the mounting bracket or the pivot bracket; a cable connector, cable interface, or interface block; and, where appropriate, pressurization controls. The mounting bracket is operable to removably secure the outer housing to a mounting structure or surface, such as, for example, a telephone pole, a building wall, or a wall or other surface within a subterranean manhole. The pivot bracket is interposable between the outer housing and the mounting bracket, being pivotably or hingedly coupled with one and fixedly coupled with the other, to allow the outer housing to be tilted up to 30xc2x0 relative to the mounting bracket, thereby both facilitating access and allowing for a greater variety of mounting locations and orientations.
The plurality of sleeves are operable to receive, retain, and interface the electronic equipment. Although not limited to housing telecommunications equipment, the equipment enclosure as described herein includes eight sleeves, each operable to house one double-wide repeater card or, with a sleeve-bisecting insert in place, two single-wide repeater cards.
The transmit and receive terminals couple with transmit and receive wires to, respectively, transmit and receive signals to and from a pendant cable. Within the pendant cable, the transmit and receive wires are separated and shielded from one another in order to reduce cross-talk or other interference. In the prior art, the transmit and receive terminals were combined in a single interface connector, thereby necessitating that the transmit and receive wires be twisted in order to maintain minimum cross-talk levels between the wires. It will be appreciated that, being labor intensive and time-consuming, such wire twisting is undesirably inconvenient and inefficient. In the present invention, however, the transmit and receive terminals are separate and distinct, thereby advantageously maintaining minimum cross-talk levels without twisting wires.
The protective circuitry, commonly including gas tube lightning surge protection circuitry, is operable to provide electrical protection for the electronic equipment. The protective circuitry is mounted on removable circuit boards, or xe2x80x9cdaughter boardsxe2x80x9d, which are located adjacent to each sleeve, and is easily accessible after removing only a lid portion of the outer housing. Thus, in contrast to the prior art, it is advantageously unnecessary to remove or otherwise interfere with operation of either the sleeves or the electronic equipment when accessing or removing and replacing the circuit boards containing the protective circuitry.
The test circuitry is operable to provide test pins or similar electrical connections for testing the operation of some or all of the electronic equipment. The test circuitry is also mounted on circuit boards, or xe2x80x9cdaughter boardsxe2x80x9d, and is easily accessible after removing only a lid portion of the outer housing. The test circuitry may include bantam jacks for advantageously facilitating easier interfacing of test equipment with the test circuitry.
The spreader plate is operable to physically force the sleeves into direct contact with the interior wall of the outer housing, thereby ensuring a direct pathway for thermal conduction from the heat-generating electronic equipment to the outer housing and the ambient environment.
The heat sink, including an upper contact surface and a plurality of leg portions depending therefrom, is advantageously operable to improve conductive heat transfer between the sleeves and the lid by providing a pathway for thermal conductivity therebetween, and is further operable to aid in retaining the electronic equipment in its proper operating position within the sleeves. In operation, waste heat generated by the electronic equipment is transferred to the legs of the heat sink (or to the sleeves and thereafter to the legs) then to the upper contact surface and then to the lid wherefrom it may be radiated into the ambient environment.
The card retainer, including a body and a plurality of leg portions depending therefrom, is advantageously operable to protect against inadvertent disengagement of the electronic equipment from the sleeves. The body secures to or is incorporated into the lid such that, when the lid is closed, each depending leg portion contacts the electronic equipment engaged within a corresponding sleeve, thereby preventing inadvertent disengagement due, for example, to movement or rough handling of the equipment enclosure. The card retainer, being secured to the lid, is removed with the lid such that no additional work is required to remove the electronic equipment from the sleeves. The card retainer may be included alternative to or in combination with the heat sink.
Thus, the equipment enclosure of the present invention provides a number of advantages, including the pivot bracket which provides an advantageous ability to pivot the outer housing up to 30xc2x0 relative to the mounting bracket, thereby both facilitating access and allowing for a greater variety of mounting locations and orientations than was possible in the prior art. Furthermore, the feature of separate and distinct transmit and receive terminals advantageously maintains minimum cross-talk and interference levels without the requiring that the transmit and receive wires be inconveniently and inefficiently twisted, as was required in the prior art. Additionally, the protective circuitry and the test circuitry is located on daughter boards adjacent the each sleeve so as to be advantageously accessible after removing only a lid portion of the outer housing, unlike the prior art which required that the repeater cards be removed or that the operation of the electronic equipment be otherwise interfered with in order to access one or both circuitries. Additionally, heat dissipation through natural conduction is advantageously improved by the spreader plate, which is operable to force the sleeves into direct contact with the interior wall of the outer housing, unlike the prior art which used complex, failure prone, and costly mechanical linkages to provide indirect contact. Heat dissipation is also advantageously improved by the heat sink which facilitates conductive heat transfer between the sleeves and the lid.
These and other features of the present invention are more fully described below in the section entitled DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT.